Methods, apparatuses, systems and software for focusing a camera

ABSTRACT

Methods, apparatuses, systems and software for focusing a camera are disclosed. The camera focusing system includes a distance measuring device, a video receiver that receives video/images, a graphics overlay unit, and a monitor. The distance measuring device includes an emitter that emits a radiation beam, a detector that detects reflected radiation, and logic that determines and processes distance information for subject(s) or object(s) in detection zones from the reflections. The graphics overlay unit receives video/image information from the video receiver and the distance information from the distance measuring device, and includes a video overlay and data processing unit that generates graphics indicating a field of detection and position for each detection zone and a direction and/or magnitude of a change in focus setting(s) to bring subjects or objects within each detection zone into focus. The monitor displays the video/image and the graphics overlaid thereon.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/286,479, filed May 23, 2014, pending, which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present invention generally relates to the field of focusing amotion picture or cinematic camera. More specifically, embodiments ofthe present invention pertain to methods, apparatuses, systems andsoftware for focusing a motion picture camera.

DISCUSSION OF THE BACKGROUND

Conventionally, the focus of a motion picture camera lens is setmanually to a distance where the plane of focus of the lens closelycoincides with the location of a photographic subject. The camera lenseshave focus distance calibrations that correspond to the distance fromthe image plane of the camera to the focus plane. Motion picture camerasmay also have an electronic mechanism for delivering the focus distancesetting through an electrical interface. The focus puller (e.g., atechnician responsible for setting the focus of the camera lens) canadjust the camera lens to the subject distance by estimating thedistance to a photographic subject and setting the focus distance of thelens to match the estimated distance, either directly or usingelectro-mechanical controls.

To estimate the focus setting for a static camera, the focus pullerconventionally uses distance cues, such as reference marks made on theground during rehearsal, or other objects whose known position relativeto the camera can serve as distance references. Provided that the focussetting corresponds to the subject being within the depth of field ofthe lens, this depth being a specified range of distances in front of orbehind the focus distance setting, the subject will appear acceptablysharp.

In many situations, the focus puller cannot achieve acceptably sharpfocus using these conventional methods. For example, when the camera ismoving during the process of shooting a scene, it is often not possibleto use pre-set focus reference marks, as the path taken by the cameramay not be predictable. In other situations, the depth of field of thelens is so shallow that the focus setting cannot be reliably estimatedby the focus puller, even when reference marks are available.

In the situations described in the previous paragraph, the focus pullermay use the image captured by the camera as displayed by a monitor toadjust the focus. However, the monitor can only show the degree to whichthe image appears to be in focus. If the image or subject is out offocus, the monitor cannot show the direction or the magnitude of anynecessary focus setting change that will bring the subject coincidentwith the plane of focus, or within the depth of field of the lens.

There have been a number of challenges to focusing a camera (or imagecaptured by the camera) using a video monitor. For example, once unclearor “buzzed” focus is observed, it is often too late to maintain or bringback focus, especially when subjects in the field of view of the cameraare in motion. Sometimes it can be difficult to tell whether one mustpull forward or backward to correct the focus. Peaking, or making theedges of objects within the image more visible (e.g., by increasing thecontrast or color of the edges, or making the edges shimmer) does notprovide much critical focusing information. Also, on many episodic TVseries, there isn't sufficient room on set for the focus pullers, andthey often work outside the set. On multiple camera shoots, there willbe one monitor and one wireless focus unit for each camera and eachassistant, thereby making demands for space for focus pullers evenhigher.

Distance measuring devices (DMD's) with single detection zones that areattached to the camera have been used both to autofocus the lens as wellas to measure the distance between the camera and the subject. Forexample, U.S. Pat. No. 4,199,246 discloses an ultrasonic ranging systemfor autofocusing a camera. Subsequent ultrasonic DMD's have beenattached to motion picture cameras to give focus pullers distanceinformation for a single subject within the detection zone of theultrasonic DMD.

The antenna pattern of an ultrasonic DMD includes a main lobe andattenuated side-lobes. Ultrasonic devices are most sensitive to targetswithin the main lobe. However, an off-axis target present in a side lobemay be detected and may cause incorrect focus. This characteristic canresult in the ultrasonic DMD indicating erroneous distance especially ifone or more targets are near the side-lobes. The single detection zonecharacteristic of ultrasonic DMD's limits the ability of the focuspuller to discriminate between multiple targets located within thesingle detection zone of the ultrasonic DMD.

An additional disadvantage of devices that provide a digital display ofthe distance to a subject is that the user needs some time to interpretthe difference between the distance display of the DMD and the presentsetting of the lens distance prior to changing the lens focus setting.The additional time that the user takes to interpret the digitalinformation increases the difficulty of maintaining sharp focus insituations where the either the subject or camera is moving quickly.

Laser ranging (LR) devices have been attached to cameras for autofocuspurposes as well as to provide distance measurements for manuallyfocusing the camera lens. Such ranging devices detect targets within asmall target detection area defined by the spot size of the collimatedlaser, and as a result, require precise targeting and tracking of thetarget. U.S. Pat. No. 8,363,152 B2 discloses such a device, where thealignment and tracking of the subject is carried out using a displaydevice reproducing the shooting image, on which the object to be focusedis selected, and the distance measurement instrument is aligned at theselected object and tracked.

Since LR devices typically have sensing beams with divergence anglesmuch smaller than the typical horizontal or vertical angle of view ofthe camera lens, the operator of the device must precisely track thetarget. LR devices can measure and indicate the distance to a subject,and with appropriate correction for parallax, indicate the focusdistance. Since the operator of the device is occupied with targettracking, the operator cannot manually alter the focus setting of thecamera lens in accordance with the distance indicated by the LR devicein a way that is consistent with the artistic intent of the scenariowithout difficulty. For this reason, LR devices may be well-suited forautofocusing, but disadvantageous for manual operation.

The disadvantage of auto-focus devices relative to manual focus controlis that the rate at which the lens focus setting matches the subjectdistance is fixed by the settings of an automatic closed loop servo inauto-focus devices. Notwithstanding the possibility of providing a userwith the facility to adjust the time response of the focus servo, theresponse must be preset in advance, precluding the matching of the timeresponse to the movement of photographic subjects as it occurs. Thisdisadvantage of autofocus devices is especially apparent when focus ischanged between subjects. In such situations, the rate of change of thefocus settings should be consistent with aesthetic considerations. Morespecifically, with reference to the movement of the subjects in certaincontexts, settings or situations, a mechanical appearance to the focuschange may be artistically undesirable.

This “Discussion of the Background” section is provided for backgroundinformation only. The statements in this “Discussion of the Background”are not an admission that the subject matter disclosed in this“Discussion of the Background” section constitutes prior art to thepresent disclosure, and no part of this “Discussion of the Background”section may be used as an admission that any part of this application,including this “Discussion of the Background” section, constitutes priorart to the present disclosure.

SUMMARY OF THE INVENTION

Embodiments of the present invention relate to methods, apparatuses,systems and software for focusing a camera. The camera focusing systemgenerally comprises (a) a distance measuring device, (b) a videoreceiver configured to receive video and/or images from the camera, (c)a graphics overlay unit, and (d) a monitor. The distance measuringdevice comprises an emitter configured to emit a beam of radiation, adetector configured to detect one or more reflections of the beam ofradiation, and logic configured to determine and process distanceinformation for one or more subjects or objects in each of a pluralityof detection zones in a field of view of the camera from thereflections. The graphics overlay unit receives video and/or imageinformation from the video receiver and the distance information fromthe distance measuring device, and comprises a video overlay and dataprocessing unit configured to generate graphics indicating (1) a fieldof detection and position for each of the plurality of detection zonesand (2) a direction and/or magnitude of a change in focus setting(s) forthe subjects or objects within each detection zone not within a depth offield of the camera. The monitor displays the video and/or images fromthe camera and the graphics overlaid on the displayed video and/orimage.

In some embodiments, the camera focusing system includes an array ofdetection zones along a horizontal axis across the field of view of thecamera. Further embodiments include a two-dimensional array of detectionzones (e.g., arranged in rows and columns). In other embodiments of thepresent camera focusing system, the graphics overlay unit furthercomprises a communication unit configured to receive information from amotor control, data processing, and communication unit on the camerathat adjusts the focus, iris, and zoom settings and transmits lenssetting data for the camera.

In some embodiments of the present camera focusing system, the graphicsindicate (1) the direction and the magnitude of the change in the focussetting(s) that will achieve sharp focus on a subject or object in aselected detection zone, and (2) each detection zone containing thesubjects or objects within the depth of field of the camera. In furtherembodiments, the graphics include a scaling that indicates the positionsof the detection zones for changing a camera focal length and angle ofview, and/or indicate a relative position of the subjects or objectswithin the depth of field of the camera.

The camera system generally comprises the present camera focusingsystem; a camera with a lens and a video transmitter unit that transmitsa video or image signal output; a motor control and data processing unitconfigured to (i) adjust focus, iris, and zoom settings of the cameraand (ii) transmit lens setting data to the video overlay and dataprocessing unit; a video receiver configured to receive the video orimage signal output; and a display device configured to display thevideo or image of the video or image signal output and the graphicsoverlaid on the video or image. In the present focusable camera system,the graphics generally include a horizontal array of detection zones. Inone embodiment, the camera is a motion picture camera, and the motionpicture camera may further comprise one or more motor and/or encoderunits configured to (i) mechanically change settings of the lensaccording to signals from the motor control and data processing unit and(ii) communicate motor positions to the motor control and dataprocessing unit. For example, the camera may include 3 motor and/orencoder units, configured to separately control the focus, iris and zoomsettings or positions of the lens.

The present camera system may further comprise a data processorconfigured to (i) correct the distances measured by the distancemeasuring device for an offset from the distance measuring device to apredetermined location in an image plane of the camera and (ii)calculate the distances along an optical axis of the camera from theimage plane to the subject(s) and/or object(s). In some embodiments, thedata processor is further configured to calculate a lens focus settingfor the subject(s) and/or object(s).

The method of focusing generally uses the present camera focusing systemto focus the camera, and embodies one or more of the inventive conceptsdisclosed herein. The software generally creates graphics that areuseful in the present method and camera focusing system.

The present invention overcomes disadvantages of autofocus devices byproviding a mechanism for the user to manually adjust the focus onmoving subjects with high accuracy, as well as providing an autofocusfunction in circumstances when manual adjustment may be challenging orimpractical due to the motion of a subject or object being too fast orunpredictable. The present invention (and in particular, the overlaidgraphics) make it possible for the user to switch between manual andautofocus modes smoothly. The present invention advantageously providesa method for the user to accurately focus the shooting lens of or on amotion picture camera by observing graphics overlaid on the imagecaptured by the camera. The overlaid graphics can indicate both thedirection and magnitude of distances, as measured along the optical axisof the camera lens, between the plane of focus of the camera lens and aplethora of subjects within a plurality of detection zones within thedetection field of a distance measuring device.

In general, the elements in the systems include a motion picture camera,a distance measuring device, a lens readout device, a motor drive/dataprocessing/communication unit, a display overlay and data processingdevice, and a video display device. The image may be captured orrecorded in the camera on an electronic image sensor, photographic film,or other medium. The live image can be made available by the camera asan electrical signal that can be displayed on a monitor. The monitor maybe integrated into the camera and/or be in a separate, stand-alonedevice. The distance measuring device measures distances and azimuthangles from its reference point to a plurality of targets. The lensreadout device generates one or more signals indicating the focusdistance setting, the f-stop, and in the case of a zoom lens, the focallength setting. The motor drive, data processing, and communication unitremotely adjusts the lens iris and the camera focus and zoom functions,and reports the lens settings (e.g., through a wireless link) to aremote processor and/or control unit. The display overlay and dataprocessing device overlays graphics and text onto a live video stream(e.g., as captured by the camera). It can also calculate the lens depthof field, and encode the overlay graphics to reflect the direction andmagnitude of the changes in lens focus settings to bring one or moresubjects in the detection field into sharp focus.

The present invention advantageously provides a focusing device thatallows a user to focus the lens of a motion picture camera on one ormore subjects simultaneously by overlaying graphics on or over the imagecaptured by the camera. The graphics indicate the direction andmagnitude of the corrections to the present lens focus setting that willfocus the camera on selected subjects in the image. The graphics canindicate the positions of the detection zones relative to the imagecaptured by the camera. The graphics can also be scaled to indicate thepositions of the detection zones for changing camera focal lengths andangles of view. The graphics can indicate which subjects are within thedepth of field of the camera lens, the relative position of the subjectswithin the depth of field of the camera lens, which of the subjects areoutside of the depth of field of the lens at its current focus setting,and the magnitude and direction of corrections in the focus settingsthat will place the subjects within the depth of field of the cameralens.

The present invention also advantageously provides a device or apparatusthat comprises a measuring device that measures each of a plurality ofdistances from itself to each of a plurality of subjects in a field ofview of a camera (e.g., within multiple detection zones in the field ofview) simultaneously; a data processing device that can correct thedistances measured by the distance measuring device for the offset fromitself to the center of the camera image plane, and can calculate thedistances along the optical axis of the camera lens from the image planeto the plurality of subjects, and thereby calculate the lens focussetting for each of the plurality of subjects; and a video overlay, dataprocessing, and communication unit that generates graphics indicatingthe horizontal field of detection and position for each detection zoneof and/or subject or object of interest in the detection field of thedistance measuring device, and can determine and display the lens focussettings for the subjects detected in the detection field and/or eachdetection zone according to information provided by the data processingdevice.

The present device or apparatus may further comprise a motor control,data processing, and communication unit that adjusts the focus, iris,and zoom settings according to signals and/or information from and/orchanges in user hand control units, and transmits lens setting data(e.g., through a wireless link) to the video overlay, data processing,and communication unit. In further embodiments, the present device orapparatus further comprises one or more motor encoder units configuredto mechanically change the settings of the camera lens according tosignals from the motor control, data processing and communication unitand communicate the motor positions to the motor control portion of themotor control, data processing, and communication unit. The presentdistance measuring device or apparatus may include a plurality ofdetection zones, and the detection zones can be arranged in a horizontalarray. The present invention further relates to a motion picture camerahaving a lens, the camera including the present distance measuringdevice or apparatus, and a video signal output, a video transmitterunit, a video receiver, and a display device.

In some embodiments, the invention comprises software (e.g., anon-transitory computer-readable medium containing recorded or encodedinstructions) which, when executed by a signal processing deviceconfigured to execute software, is configured to create or generategraphics to be overlaid onto a video or image, or perform part or all ofthe method(s) discussed above. These and other advantages of the presentinvention will become readily apparent from the detailed description ofvarious embodiments below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a representation of an exemplary motion picture cameraincluding a distance measuring device, a wireless lens control unit, alens focus control motor, and a wireless video transmitter.

FIGS. 2A-B are representations of an exemplary wireless video processingunit including a graphics overlay unit (FIG. 2A), and an exemplary hand(manual) control unit (FIG. 2B).

FIG. 3 shows a graphical representation for determining the distancesseparating the camera sensor of the camera, the sensor of the distancemeasuring device, and the entry pupil of the camera lens.

FIG. 4 is a graphical representation showing exemplary horizontal andvertical angles of view of the motion picture camera, and exemplaryhorizontal and vertical angles of detection of the distance measuringdevice, for determining the distance of an object from the image planeof the motion picture camera.

FIG. 5 is an exemplary representation of an image captured by the motionpicture camera overlaid by graphics to show the user the direction andmagnitude of the change in focus lens setting that will place one ormore of the subjects within the horizontal and vertical fields ofdetection of the distance measuring device within the depth of field ofthe camera lens.

FIG. 6 is an exemplary representation of an image captured by the motionpicture camera overlaid by a graphic in accordance with an auto-focusmode of the invention.

FIG. 7 shows an exemplary image with distance measurements for all ofthe detection zones in a distance ranging mode of the invention.

FIG. 8 is a flow chart of an exemplary method of focusing a motionpicture camera on one or more subjects within the detection zone(s) ofthe distance measuring device that are within the depth of field of thecamera lens.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. While the invention will be described in conjunction with thefollowing embodiments, it will be understood that the descriptions arenot intended to limit the invention to these embodiments. On thecontrary, the invention is intended to cover alternatives, modificationsand equivalents that may be included within the spirit and scope of theinvention as defined by the appended claims. Furthermore, in thefollowing detailed description, numerous specific details are set forthin order to provide a thorough understanding of the present invention.However, it will be readily apparent to one skilled in the art that thepresent invention may be practiced without these specific details. Inother instances, well-known methods, procedures, components, andcircuits have not been described in detail so as not to unnecessarilyobscure aspects of the present invention.

The present invention provides an apparatus and method that can indicatesimultaneously the focus status of multiple subjects in an image by acamera and shooting lens, where the focus status indications show boththe direction and distance, as measured along the optical axis of thecamera and lens, of the subjects from the plane of focus of the shootinglens. The focus status indications are shown in a display, and includegraphical elements overlaid on the image captured by the camera. Thegraphical elements indicate the magnitude and direction of the change inlens focus setting(s) that will bring one or more of the subjects and/orobjects in the field of view of the camera into sharp focus (e.g., afocus setting such that no further or additional detail can be gained inthe desired or selected subjects and/or objects as captured by thecamera by any further or additional change in the focus setting). Thegraphical elements overlaid on the display are much easier and/or fasterfor a user to interpret than conventional digital information displays.The invention thereby allows the user to simultaneously view the imagecaptured by the camera, manually control the rate of change in the focussetting of the camera lens in accordance with the artistic requirementsof the photography, and achieve high accuracy in focusing the lens onone or more subjects in the field of view of the camera.

The invention disclosed herein gives the user clear visual prompts inthe form of graphics that show both the direction and magnitude thatwill bring the lens focus setting to the position of a particularsubject in the field of view of the camera. The graphics shown on thedisplay allow the user to concentrate on adjusting the focus settings inaccordance with the movement of the photographic subjects, rather thanestimating the focus distance to the subject. The present invention, byallowing accurate manual adjustment of focus, avoids any appearance ofartificial and/or mechanical focusing that can result from the use of afully automatic focus control system.

The invention concerns a distance measuring and/or focusing device thatallows the user to focus the lens of a motion picture camera on one ormore subjects simultaneously by overlaying graphics on or over the imagecaptured by the camera, the graphics indicating the direction and/ormagnitude of the corrections to the present lens focus setting that willachieve a sharp focus on selected subjects (e.g., within a selecteddetection zone). The graphics indicate the positions of the detectionzones (and/or one or more objects in the detection zones) relative tothe image captured by the camera. The graphics may also be scaled toindicate the positions of the detection zones for changing camera focallengths and/or angles of view, indicate subjects that are within thedepth of field of the camera lens or the relative position of thesubjects within the depth of field of the camera lens, and/or indicatewhich of the subjects are outside of the depth of field of the lens atits current focus setting. In a further embodiment, the graphics canindicate or display the magnitude and/or direction of corrections in thefocus settings that will place the subjects within the depth of field ofthe camera lens. The detection zones of the distance measuring devicemay be arranged in a horizontal array.

The invention also concerns a device (e.g., a focusable camera system)that comprises a distance measuring device that simultaneously measuresthe distance from itself to a plurality of subjects in multipledetection zones of the field of view of a camera; a data processingdevice that corrects the distances measured by the distance measuringdevice for the offset from itself to the center of the camera imageplane, and that in a further embodiment, calculates the distances alongthe camera lens optical axis from the image plane to a plurality ofsubjects, thereby calculating the lens focus setting for the pluralityof subjects; a video overlay, data processing, and communication unitthat generates graphics that indicate the horizontal field of detectionand the position of each detection zone of the distance measuringdevice, as well as one or more lens focus settings for the subjectsdetected within each detection zone; a motor control, data processing,and communication unit that adjusts the focus, iris, and zoom settings(e.g., according to user hand control units) and transmits lens settingdata (e.g., through a wireless link) to the video overlay, dataprocessing, and communication unit; one or more motor encoder unitsconfigured to mechanically change the settings of the camera lensaccording to one or more signals from the motor control, data processingand communication unit, and optionally, communicate the motor positionsto the motor control unit; and a motion picture camera with a lens, thecamera having a video signal output. The camera may further comprise avideo transmitter unit, and the system may further comprise a videoreceiver (e.g., that receives the output of the video transmitter unit).In one embodiment, the video transmitter unit and the video receivercommunicate wirelessly. The system also generally comprises a displaydevice, which may be stand-alone or integrated with the camera or thedistance measuring device, on which the graphics are displayed, and thatthe user (e.g., a focus puller) can view and interact with. In variousembodiments, the detection zones of the distance measuring device arearranged in a horizontal array.

The invention, in its various aspects, will be explained in greaterdetail below with regard to exemplary embodiments.

An Exemplary Distance Measuring System and an Exemplary Camera SystemIncluding the Same

Referring now to FIG. 1, the camera system as shown includes two units,a camera 1 and a sensor or distance measuring unit 5. The sensor ordistance measuring unit 5 may be placed or fixed atop the camera 1, forexample above the lens 2, or to a side of the camera 1 as shown inFIG. 1. Using parallax correction (which may be found in an on-screenmenu; see the discussion below), the sensor or distance measuring unit 5can be placed anywhere that is convenient for the user(s). A relativelyquick setting can calibrate the offset (see the discussion herein).

As discussed herein, a motor control, data processing and communicationunit MCDPU is attached to the camera 1, and one or more (e.g., aplurality of) electric motor/encoder units MEUs are coupled to the lensgear(s) or gear ring(s) of the camera to allow the lens focus setting(and optionally, the lens focal length and/or iris) to be controlledremotely by a remote manual control (hand) unit RMCU. The remote handunit RMU in communication with the camera transmits both motor commandsand lens calibration data to the MCDPU so that the MCDPU has at eachmoment the lens focus setting distance for each of a plurality ofsubjects and/or objects in the field of view of the camera. In oneembodiment, the RMU communicates with the MCDPU via a wirelesscommunication link.

The distance measuring device (DMD) 5 has a plurality of detection zonesthat may be arranged horizontally as a line array within its field ofdetection. The DMD is affixed to the camera and oriented so that (1) itsline of sight is parallel to the line of sight of the camera, and (2)the horizontal axis of the camera sensor is parallel with the DMD fieldof detection (e.g., the detection zones). The DMD measures distancesfrom its reference plane to subjects within its field of detection(e.g., in each of its multiple detection zones) simultaneously andprovides data to the MCDPU on the distances, as well as the detectionzones associated with the measurements when the DMD has plural detectionzones. In some embodiments, the array of detection zones fills orsubstantially fills the field of view of the camera. Generally, thedetection zones do not overlap, and in certain embodiments, thedetection zones in the array are tiled (e.g., adjacent to each other ina one- or two-dimensional pattern). Each of the DMD detection zones mayhave an associated azimuth angle measured relative to the DMD line ofsight so that the radial measurement of distance combined with theazimuth angle associated with the DMD detection zone define a vectorwhose component parallel to the optical axis of the camera is found bytaking the product of the radial distance with the cosine of the azimuthangle.

In one implementation, distance detections performed by the DMD areresolved into angular increments approximately equal to the horizontalangle of detection of the DMD divided by the number of detection zones.The number of DMD detection zones and the horizontal angle of detectioncan be selected such that any error in the calculation of focus distancesetting due to the finite size of the increments in azimuth angle isnegligible for the specified range of operation and the desired orpredetermined accuracy.

The camera system generally further includes two additional units, avideo processing unit 100 and a hand control unit 150, exemplaryembodiments of which are shown in FIGS. 2A-B. The video overlay andprocessing unit VOPU generates graphics to overlay onto the imagecaptured by the camera. The graphics indicate, for each object in thefield of view and/or detection zone of the DMD, the magnitude and thesign of the difference in distance between the subject or subjects inthe field or in each zone, and optionally, the lens focus setting(henceforth, the “subject focus status”). A wide variety of graphicalmeans can be utilized to encode the subject focus status, including butnot limited to altering the color, brightness, or contrast of theunderlying picture, overlaying graphic elements whose geometry varies,adding patterns of texture, and adding edge outlines to the images ofsubjects in the field of view or within DMD detection zones whosecharacteristics change with focus status. Additional data, including thelens focal length, T-stop setting, camera type, near and/or far depth offield distances, and/or image plane-to-subject distance measurements,can be displayed at the option of the manufacturer and/or user.

In one exemplary embodiment, the VOPU generates a graphical imageincluding an array of horizontally arranged rectangular outlines, eachof the outlines corresponding to a detection zone of the DMD within thefield of view of the camera. The shape of the outlines can besubstantially any regular geometric shape, such as circular, oval,square, hexagonal, octagonal, elongated hexagonal or octagonal, etc. Thearray of horizontally arranged outlines overlays the image captured bythe camera with the graphics, and the resultant composite image is shownon a display. The width of each of the outlines appearing on the displaycorresponds to the horizontal angle of detection of the correspondingdetection zone. Thus, the width of each of the outlines may be the sameacross the display, or may vary as a function of the distance of theoutline from the center of the display or of the field of view of thecamera. Different outlines distinguish between subjects that are withinthe depth of field of the camera lens, and objects that are outside thedepth of field.

For subjects that are outside of the depth of field of the camera lens,in one embodiment, the outlines have one edge collinear to a median lineextending horizontally across the display, and optionally, bisecting theheight of the display. The focus status for subjects within eachdetection zone, but outside of the depth of field of the lens, isindicated by the height of the outline, which corresponds or is relatedto the difference between the focus setting distance and the distancefrom the subjects to the image plane of the camera.

In the present invention, the scale relating the height of the outlinesto the difference in distance D between the subject in the outline andthe plane of focus of the camera lens may be set by the user. In someembodiments, for subjects closer than the close limit of the lens depthof field, the minimum distance displayed from the median line of thedisplay to the lowest display position is kD, where k is a number 0<k<1,and for subjects farther than far limit of the lens depth of field themaximum distance displayed is D/k. If desired, these relationships canbe reversed. The scaling may be customized (e.g., to user preferences)by choosing the value of k. For example, k may equal 0.5.

Outlines that correspond to subjects closer to the camera than the planeof focus, but outside of the lens depth of field, may extend from themedian line downwards, while outlines that correspond to subjectsfarther from the camera than the plane of focus, but outside of thedepth of field of the camera lens, may extend upwards from the medianline. Alternatively, outlines that correspond to subjects closer to thecamera than the plane of focus, but outside of the lens depth of field,may extend upwards from the median line, while outlines that correspondto subjects farther from the camera than the plane of focus, but outsideof the depth of field of the camera lens, may extend downwards from themedian line.

Whenever a subject within a detection zone is within the depth of fieldof the camera lens, the outline representing that zone on the displaymay change to a fixed height (e.g., from 25% to 50% of the height of thedisplay, and in one example, approximately 33% of the height of thedisplay) and/or be centered on the central horizontal axis of the array(e.g., the median line). Alternatively or additionally, the color of theoutline may change to make its identification to the user immediatelyapparent. The outlines may move vertically so that the intersection ofthe median line along the vertical extent of the rectangle indicates therelative position of the subject within the lens depth of field (e.g.,the median line may extend downwards when the subject is closer to thecamera than the plane of focus and within the lens depth of field, andthe median line may extend upwards when the subject is farther from thecamera than the plane of focus and within the depth of field of thecamera lens, or vice versa).

The VOPU may scale the graphics, indicate the DMD detection zones, andcorrect the position of the detection zones on the display so that thewidth and position of the outlines (e.g., rectangles) including thegraphics accurately overlay the corresponding areas of the camera image.The lens angle of view is sent to the VOPU by a motor drive unit (e.g.,through a wireless link). To accommodate variable focal length lenses,the focal length of which may change during the shooting of a scene, theangle of view information is transmitted with sufficient speed that theoverlaid graphics smoothly follow change scales in the lens angle ofview.

The VOPU calculates the parallax corrections that correctly position theoverlay graphics using the two orthogonal components of the vector B(e.g., Bx along the horizontal axis of the camera image sensor, and Bzalong the vertical axis of the image sensor of the DMD), known ordeterminable from the method and/or manner in which the DMD is fixed tothe camera. In addition, to accommodate other mechanisms of fixing theDMD to the camera, the user may be given an option to enter horizontaland vertical offset values (e.g., through a set-up menu on the display).In some embodiments, the VOPU may generate additional graphics toindicate the vertical angle of view of the detection zones as correctedfor parallax.

Since the display may be remote (e.g., a distance from the camera thatmay make the transmission of data by electrical cable from the DMDand/or the focus control unit to the VOPU inconvenient), one exemplaryembodiment of the invention uses a wireless link for the transmission ofsuch data. Also, a wireless link (e.g., the same or different wirelesslink) may be used to transmit the video signal from the camera to theDVPI.

Although laser distance ranging devices of a type that performmeasurements within a single detection zone have been used to autofocuscamera lenses, their fully automatic operation may result in the focuschanges having a mechanical appearance. This mechanical appearanceresults from the autofocus control loop effecting focus changes at afixed rate, independent of artistic requirements. Nonetheless, there maybe situations in which an auto-focus capability is advantageous (e.g.,documentary or journalism filming, in which subjects may act in anunexpected or unpredictable manner), and the present invention alsoencompasses motion picture cameras and focusing mechanisms andapparatuses that include an auto-focus function.

FIG. 1 shows an exemplary camera 1, including a zoom objective lens 2,motor control, data processing and communication unit MCDPU 3, a videotransmitter unit 4, a distance measuring device (DMD) 5, and a digitalvideo camera 24. The objective lens 2 includes a plurality of lens gearsor gear rings 10-12, configured to adjust or change the focus, iris andzoom settings of the lens 2. The camera 1 includes a plurality of motorsand/or encoders 7-9, configured to drive the lens gears or gear rings10-12 using gears 17, 18 and 19 a-b. The video transmitter unit 4includes an antenna 13 configured to broadcast a video signal capturedby the camera 1.

The motor control, data processing and communication unit MCDPU 3includes a plurality of receptacles 25 for transmitting electricalsignals to the motors and/or encoders 7-9 (e.g., using wires or cables),one or more switches 29 for selecting the wireless communication channelfor the MCDPU 3, one or more corresponding displays or indicators 30(e.g., indicating the communication channel for the MCDPU 3, or that theMCDPU 3 is on or off), and an antenna 28 for wirelessly transmittingsignals to the motors and/or encoders 7-9 and/or receiving wirelesssignals from a video overlay and data processing unit (FIG. 2A). TheMCDPU 3 also includes circuitry and/or logic configured to convert thesignals and/or information from the video overlay and data processingunit into signals that cause one or more of the motors and/or encoders7-9 to change or adjust a corresponding focus, iris and/or zoom gearring to a desired or predetermined setting.

The DMD 5 comprises an emitter 6 configured to emit a radiation beam, areflected beam detector 14, and circuitry and/or logic configured todetermine or calculate a distance for each of a plurality of subjectsand/or objects in the field of view of the camera 1 from the emittedbeam and the reflected beam. In one embodiment, the emitter 6 comprisesa light-emitting diode (LED) that emits infrared (IR) light. Theradiation beam emitted by the emitter may have a fan shape and/or acharacteristic spreading angle (e.g., of from 5° to 45°, from 10° to30°, or any other angle or range of angles within the range 5-45°). TheIR light may comprise broadband IR light, to improve the uniformity ofthe response of the reflected light across a broad range of subject andobject types. Alternatively, the IR light may comprise narrow band IRlight, which may reduce costs and/or facilitate manufacturing and/oroperations of the system.

The motion picture camera 1 shown in FIG. 1 captures images from a zoomobjective lens 2. The focus, iris, and zoom functions of the objectivelens 2 are adjusted by the focus lens gear 10, the zoom lens gear 11,and the iris lens gear 12. The gear 18 of motor/encoder 8 is coupled tothe focus gear 10, the gears 19 a-b of motor/encoder 9 are coupled tothe zoom gear 11, and the gear 17 of motor/encoder 7 is coupled to theiris gear 12. Motor/encoders 7-9 are controlled by the motor controldata processing and communication unit MCDPU 3. The video transmitterunit 4 sends the image captured by camera 1 wirelessly via the antenna13 to a video receiver 121 (see FIG. 2A).

FIG. 2A shows an exemplary video processing unit 100, including a videoreceiver 121 equipped with an antenna 113, a graphics overlay unit 140equipped with an antenna 142 and a connector 145 configured to receivethe video signal from the video receiver 121, and a monitor 130 having adisplay screen 135. The monitor 130 may further comprise a controlblock/interface 136 (including a plurality of controls for changing oradjusting the energy mode [e.g., battery-powered operation or pluggedin], marker, WFM, zoom, aspect ratio, selecting the user and/or inputsource, and/or making other adjustment[s]), a menu display on/off button137, a power on/off button 138, and a tally indicator 139 that indicateswhether the selected camera/input source is recording or not. Inaddition to displaying the video and/or image with the present graphicsoverlaid thereon, the monitor 130 can also display lens data in apredetermined region of the display 135 (e.g., in a separate bar at thebottom of the screen). The lens data may include one or more of thefollowing: focus distance, the iris setting(s), the focal length of thelens, and endpoints of the depth of field range (i.e., the depth offield near distance and the depth of field far distance).

FIG. 2B shows an exemplary hand control unit 150, including a digitaldisplay 115 for use in calibrating the camera and using the focus, irisand zoom motor controls, camera start/stop indicators 117 and 123, acontrol interface 124 (for calibrating the lens, such as the zoomfunction/settings), a zoom controller 116, a focus knob 119, an iriscontrol slider 120, a switch 122 for selecting menu items on the display115, soft input keys 125 for selecting certain displayed items orfunctions on the display 115, a ring selector 118 for selecting a focusdistance, a witness mark 127 that indicates the focus distance selectedusing the ring selector 118, a focus knob 119, and a set of limitselection keys 126 configured to allow the user to select limits for thefocus, iris and/or zoom motors (e.g., motors 7-9 in FIG. 1). The zoomcontroller 116 may comprise a pressure-sensitive joystick, in which thepressure applied to the joystick controls the rate or speed with whichthe camera changes the focus, iris and/or zoom.

The video graphics overlay and (data) processing unit VOPU 140 can beattached electrically (and optionally, mechanically) to the monitor 130.The video overlay unit 140 receives focus information from both the DMD5 and the hand control unit 150 (FIG. 2B). A beam of radiation (e.g.,infrared light) from the DMD emitter 6 reflects or bounces off objectsin the scene (e.g., the field of view of the camera). The angle of theradiation may be from 5° to 45° (in one example, it is about 18°), andits range can be up to about 300 meters or 1000 feet (in one example, itis about 50 meters or 150 feet). The reflected beam is captured by adetector array behind the lens 14 of the distance measuring unit 5. Ingeneral, the detector array corresponds to the array of detection zonesto be generated by the VOPU 140. For example, the detector array maycomprise a single row of from 4 to 64 detectors (e.g., 16 detectors), ora two-dimensional array of x rows of detectors by y columns ofdetectors, where x and y are each integers of at least 2 (e.g., 2≦x≦8;4≦y≦64). The detector array may comprise an array of image detectorsintegrated onto a single substrate or as discrete devices. Consequently,the present distance measuring device or unit can avoid the use ofnarrowly collimated lasers (thereby eliminating consequent eye safetyissues) and ultrasonic signals, and transponders need not be attached tothe actors or other moving subjects in the field of view of the camera.

Referring back to FIG. 1, MCDPU 3 positions the gears of motors and/orencoders 7, 8, and 9 in accordance with the motor position informationand/or data sent by controls 115 and 117 (shown in FIG. 2). Rotation ofthe focus knob 119 controls the position of the gear of motor/encoder 8,linear motion of the iris knob 120 controls the position of the gear ofmotor/encoder 7, and pressure on the zoom control knob 116 controls theposition of the gear of motor/encoder 9. The focus, iris, and zoomsettings of the lens may be referred to herein as lens settings. Thelens settings are transmitted by user hand control unit 150 via awireless link (e.g., including antenna 113) to the MCDPU 3 (FIG. 1) inthe form of serial digital data. The lens settings may also be sentdirectly to the MCDPU 3 by lenses that provide their lens data throughan electrical interface (not shown).

Distance measuring device DMD 5 is generally a fixed and/or knowndistance from the focal plane 220 of the camera 1. The line of sight ofthe DMD 5 is parallel to that of the camera lens optical axis (e.g.,OA1; see FIG. 3), and the displacement of the central detection area 210of the DMD 5 from the center of the camera focal plane 220 is shown interms of the x and y components (and alternatively, of the x, y and zcomponents) of the vectors A and B in FIG. 3. The MCDPU 3 (FIG. 1)receives distance data from DMD 5, and transmits both the distance dataand the current focus distance setting that the MCDPU 3 receives fromthe user control 115 (FIG. 2) to the video overlay and processing unitVOPU 140.

Exemplary Methods of Determining a Camera-to-Subject Distance andCorrecting for the Camera-to-Distance Measuring Device Offset

FIG. 3 shows the geometric and spatial relationships between thereference plane 210 of the distance measuring device, the image plane220 of the camera, and the eye pupil 230 of the camera lens. Thereference plane 210 is the array of sensors in the distance measuringdevice that detect reflected radiation. The relationships shown in FIG.3 are useful for determining the offset of the distance measuring devicefrom the image plane 220 of the camera.

FIG. 4 shows exemplary relative positions of the camera 1, lens 2, DMD5, the horizontal angle or width αh of the object plane 270 (the planeon which the lens is focused) at the distance of the subject S1, and thehorizontal angle or width θh of the intersection 275 of the horizontalangle view of the DMD 5 detection array with the object plane 270. FIG.4 also shows the difference or offset δh between the optical axis OA1 ofthe camera 1 and the optical axis OA2 of the DMD 5. Although the DMD 5can simultaneously measure multiple subjects in all of the detectionzones 251-266, for the sake of clarity, a single subject S1 (e.g., acalibration subject) is shown in the DMD detection zone 260 at theazimuth angle β.

Because the camera image plane is not coincident with the DMD referenceplane, and the camera lens optical axis is not coincident with the DMDoptical axis, the VOPU calculates the subject-to-image plane distance bycorrecting the distances measured by the DMD 5 (see, e.g., FIG. 4) toaccount for the separation between the DMD 5 and the camera image plane(e.g., 220 in FIG. 3). Since lenses used in the cinema or motion picturearts generally have substantially flat planes of focus, and lens focusdistance calibrations are referenced from the camera image plane (e.g.,220 in FIG. 3) along the camera lens optical axis OA1 to the plane offocus, for each of the subjects detected by the DMD 5, the VOPUcalculates the distance Cy (the camera image plane-to-subject distance;see FIG. 4) along the optical axis of the camera OA1 from the imageplane of the camera (e.g., 220) to the intersection S1 of the opticalaxis with the plane of focus 270 for the subject (e.g., a calibrationsubject). Cy is calculated by adding or summing a vector A, directedfrom the image plane 220 of the camera (FIG. 3) to the entrance pupil EP(FIG. 4) of the lens 230 (FIG. 3), a vector B, directed from theentrance pupil EP (FIG. 4) of the lens 230 (FIG. 3) to the intersectionpoint of the DMD reference plane 210 and the DMD optical axis OA2(henceforth referred to as the center of the DMD reference plane), and avector F (FIG. 4), directed from the center of the DMD reference plane210 (FIG. 3) to the subject (e.g., S1; FIG. 4); and calculating thecomponent of the resultant vector that is parallel to the optical axisOA1 of the DMD 5. The vector A (FIG. 3) may lie along an optical axisOA1, in which case its component along the optical axis is |A|, itsabsolute value. By (FIGS. 3-4), the component of vector B along an axisparallel to axis OA1, may be calculated or determined by calibration.Fy, the component of the vector F (FIG. 4) directed along an opticalaxis OA2 of the DMD 5 (FIGS. 3-4), may be calculated or determined bymultiplying the distance |F| measured from the center of the DMD 5 tothe subject by the cosine of the angle β (FIG. 4) subtending vector Fand the axis OA2.

According to the foregoing, Cy is the following sum: |A|+By+|F|cos β.The first two terms are distances that are found, calculated ordetermined in a calibration step, in which the user places a target at adistance Ey along the optical axis OA2 of the DMD 5, and adjusts thefocus of the lens to maximize the sharpness of the target (e.g., asshown on the display). The DMD 5 measures |Fc|, the distance from theDMD 5 to the target, as well as the angle βc (e.g., the azimuth angle ofthe calibration target). The distance from the camera image plane 280(FIG. 4) along the camera optical axis OA1 to the calibration target S1(FIG. 4) is Cy=|A|+By+|Fc|cos βc. In such an example, the distances |A|and By are defined by the equation: |A|+By=Cc−|Fc|cos βc, where Cc isthe known distance (e.g., from lens calibration) from the lens to thetarget (e.g., along optical axis OA1). Using the aforesaid calibrationdata, the VOPU calculates Cy according to the equation: Cy=Cc−|Fc|cosβc+|F| cos β.

FIG. 4 shows the DMD 5 in a preferred embodiment with 16 detection zones251-266 arranged in a horizontal array. However, the DMD 5 may have anyplural number of detection zones (e.g., at least 4, from 4 to 256 or anyrange therein, such as from 4 to 64, etc.). The array 251-266 has ahorizontal angle or width of detection θh and a vertical angle or heightof detection θv. The camera 1 has a horizontal angle of or width view αhat the focal distance of the subject S1 and a vertical angle or heightof view αv. The angle or distance δv represents the height from thebottom of the intersection 275 of the DMD vertical angle of detectionwith the object plane 270 to the horizontal axis of the detection zones251-266 as displayed in the graphics to be overlaid on the video/image.The vector B, the parallax offset between the entrance pupil EP of thecamera lens 2 and the DMD 5, is directed from the entrance pupil EP ofcamera lens 2 to the center of the DMD 5 image detector. The opticalaxis OA1 of the camera 1 is parallel to the optical axis OA2 of the DMD5.

Referring now to FIG. 3, Bx, the x component of the vector B, results ina horizontal shift of the center of the array of graphic elements(representing the detection zones 251-266) with respect to the center ofthe image captured by the camera 1 and shown on display 135 (FIG. 2) byan amount w*δh/αh, where w is the horizontal dimension of the activearea of the display 13, and αh=tan⁻¹(Bx/Dy). In the example shown inFIG. 4, the graphic elements comprise rectangular elements or outlines.Bz, the z component of the vector B, results in a vertical shift of thecenter of the array of graphic elements by the amount v*δv/αv, where vis the vertical dimension of the active area of the display 135, andαv=tan⁻¹(Bz/Dy).

The VOPU 114 shown in FIG. 2 uses the known components of the vector Aand Cy (the known focus distance of the camera, as measured from theimage plane 280 of the camera; see FIG. 4) to shift the position of theoverlay graphics in both the horizontal and vertical directions so thatthe outlines (e.g., rectangles 301-316 in FIG. 5) constituting theoverlay graphics are positioned over the corresponding areas of theimage captured by camera 1 and shown in the display 113. The VOPU 114generates graphics indicating the focus status of subjects within theplurality of detection zones 251-266 of DMD 5 and overlays the focusstatus graphics onto the camera image received by the wireless videoreceiver 121 (FIG. 2A).

The VOPU 114 calculates the y-component of the distances from theplurality of subjects within the detection zones 251-266 of the DMD 5 tothe camera image plane 220 (FIG. 3) by summing the y-components of thedistance of each subject detected by the DMD 5 with the y-component ofthe vector B, the known displacement of the DMD 5 relative to the cameraimage plane 220. Since the DMD 5 has a small vertical angle of view, andthe z-component of the vector B is assumed or presumed to be smallrelative to the minimum usable subject-to-image plane distance, thevectors directed from the sensor 210 of the DMD 5 to any of the plethoraof subjects in the field of view of the camera 1 are assumed to lie inthe x-y plane, and their y-components are determined or calculated bymultiplying their distances by the cosine of the azimuth angle for thecenter of the corresponding detection zone 251 through 266.

Exemplary Graphics Overlaid on an Image

FIG. 5 shows a representation of an image 300 captured by the camera 1and with graphics overlaid by the VOPU. The horizontal median line 325spans the image 300 from the left edge of the first detection zone 301to the right edge of the last detection zone 316, and is the referencefrom which the heights of the detection zone shapes (e.g., rectangles)are measured. The rectangles in the exemplary embodiment of FIG. 5 areopen so that the underlying camera image can be clearly seen. Theheights of the rectangles from the median line 325 indicate themagnitude and direction of the difference between the focus setting ofthe camera lens 2 and the distance from the subject(s) in each detectionzone 301-316 of the DMD 5 to the image plane 220 of the camera 1. Thewidth of each of the rectangles occupies the same horizontal angle ofview in the composite image 300 as the horizontal angle of view dividedby the number of detection zones represented by each of the DMDdetection zones 301-316. For example, the height of rectangle 302 abovethe median line 325 indicates that the distance within the encloseddetection zone 302 is greater than both the lens setting distance Cy andthe far limit of the lens depth of field Cy+δy^(far). The height of therectangle 303 below the median line 325 indicates that the distancemeasured within the enclosed detection zone 303 is less than either thelens setting Cy or the near limit of the lens depth of fieldCy−δy^(near).

The sides of rectangles 307, 308 and 315 are colored to indicate thatthe distance measured within the enclosed detection zones 307, 308 and315 is within the depth of field of the lens. The depth of field of thelens is calculated using the known settings for lens f-stop, lens focallength, and focus distance. An advantage of the present graphics is thatit becomes intuitive to pull focus, because the graphics can show thedirection and/or magnitude to turn the knob or adjust another control ofa wireless hand camera unit to bring objects into sharp focus.

In the example shown in FIG. 5, the overlaid graphics include 16focus/detection zones 301-316. The array may have an appearance similarto that of a bar graph. Each zone may have, for example, a white bar atthe top or bottom, the height of which indicates the distance anddirection that a subject (e.g., the main subject) in the zone is fromthe plane of focus of the camera. The zone color may change (e.g., fromwhite to green) when a subject in the zone is within the lens depth offield. Zone or white bars above the median line 325 are behind the planeof focus of the camera. Zones or white bars below the median line 325are in front of the plane of focus of the camera. Green bars orrectangles show zones that are in focus, and thus automatically show thedepth of field, calculated by lens focal length, distance and T-Stop.The graphics overlaid on the image 300 (e.g., shown on a monitor such asmonitor 135 in FIG. 2A) thus show the distance and the direction thesubject is from the plane of focus. The user does not need to comparelens focus setting(s) to distance measurement(s).

Exemplary Additional Embodiments

In cases where the movement of subjects is too rapid to follow manually,an autofocus function is advantageous. Thus, in further embodiments, thepresent focusing system and camera further include auto-focus (AF)capability. For example, the present line sensor detector (e.g., DMD 5,FIGS. 1 and 4) may further include control circuitry, motor(s), andsoftware/programming enabling the camera lens to automatically focus ona selected object in a given detection zone. The focusing system,detector and/or camera may further include a switch that turns theauto-focus function on and off.

In the auto-focus mode (e.g., the switch turns the auto-focus functionon), the positions of the detection zones may be shown by a horizontalarray of rectangles and/or other shapes. The zone or group of zonesselected by the user using a switch, touchscreen, pull-down menu orother user selection or entry mechanism is displayed or indicated on thegraphics overlaying the camera image. For example, selection of aparticular zone or zones may be shown by changing the graphics (e.g., bychanging the color of the selected rectangle).

In one embodiment, as shown in FIG. 6, when the user selects theauto-focus function, the array of detection zones is replaced by asingle auto-focus detection zone overlaid on the video or image,outlining the area of a group of detection zones (e.g., a center groupof detection zones) from the array. In the auto-focus mode, the lensfocus is set on the closest subject or object (e.g., the shortestdistance measurement) in one or more of the user-selected detectionzones. For example, when x detection zones are arranged in a horizontalarray (where x is an integer of at least 4) in the manual focusing mode,from 25% to 50% of the detection zones of the array are replaced (e.g.,automatically or by user selection) in the auto-focus mode with anauto-focus detection zone. For example, from x/4 to x/2 of the xdetection zones in the center of the array may be replaced with anauto-focus detection zone, although some embodiments may allow for morethan one auto-focus detection zone. In one implementation, a horizontalarray of sixteen rectangles (see FIG. 5), the six center detection zones(rectangles) are replaced by a single rectangle 317 (FIG. 7) over thevideo or image 300′.

In one variation, the video processing unit (e.g., 100 in FIG. 2A)allows the user to select the number of detection zones and theirposition real-time (e.g., “on the fly”). Alternatively or additionally,the user can make auto-focus selections (e.g., for configuration of theauto-focus detection zone) via user controls on the hand control unit(e.g., 150 in FIG. 2B). Further variations allow the user to select thespeed with which focus changes are made, the relative position of thesubject/object on which to measure distance and/or auto-focus (e.g.,nearest, farthest, in the center of the detection zone, etc.), etc.

In one embodiment, the auto-focus mode is entered by selecting anappropriately labeled menu item displayed on the hand control unitdisplay 115 (e.g., pressing a soft input key 129 [FIG. 2B] below an itemlabeled “Auto-focus”). Upon entering the auto-focus mode, the lens mayfocus on the closest subject in the auto-focus detection zone 317 (FIG.6), which may be a center portion of the detection zones in the arraydisplayed in the manual focus mode, as described herein. As shown inFIG. 6, a red rectangle 317 overlays the image 300′ on the monitor(e.g., 135 in FIG. 2A) to outline the autofocus detection zone. Toreturn from the autofocus mode to the manual focus mode, the user simplypresses the autofocus mode selection soft key 129 again. Alternatively,in one embodiment, the user can set the focus knob 119 (FIG. 2B) tomatch the focus distance shown on the monitor 135 (FIG. 2A). In oneexample, both the focus distance measurement and the focus knob settingare shown on the monitor 135. When the user presses the autofocus modeselection soft key 129 again, the system returns to manual focus modewithout a focus jump.

Further embodiments of the present invention may include or employmulti-line and/or two-dimensional (2D) detection and/or sensing, eithermanually or in combination with the autofocus function described herein.A multi-line or 2D sensor can provide focus information for subjects notcovered by the vertical angle of view of the line detection sensor(e.g., DMD 5). The operator can choose which detection line is activeusing a switch or a touch screen function on the video monitor. The bargraph display is centered on the overlaid image as described with regardto the present line detection sensor, but one or more horizontal linesare added to indicate the vertical limits of the selected detectionzones. For example, a pair of horizontal lines can be added to thedisplay, one above and one below a center line (e.g., the horizontalline of the line detection sensor described above).

The multi-line/2D detection sensor can also be equipped with anautofocus (AF) operation. In one embodiment, the display has a 2D arrayof rectangles or other shapes overlaid on the image from the camera toindicate the detection zones. The user can then choose which of theoverlaid rectangles or shapes in which the AF distance is measured usinga joystick, mouse, a touch screen function on the video monitor, orother selection mechanism. In a further embodiment, an autofocustracking mode can use motion estimation to automatically select whichdetection zone provides the desired autofocus distance data.

In one further embodiment shown in FIG. 7, a relatively simple distanceranging mode shows distance measurements for all of the detection zones351-366 on an image 350 simultaneously when distance and/or focusinformation is to be obtained quickly, or (for example) when a usercannot run a focus tape. In such an embodiment, the predetermined region370 of the display for showing lens data may instead display thedistance of the subject or object in each of the detection zones351-366.

An Exemplary Method

The present invention further relates to method of focusing a camera,comprising simultaneously determining a distance from a distancemeasuring device to one or more subjects and/or objects in each of aplurality of detection zones of the distance measuring device;generating graphics indicating (i) a field of detection and a positionfor each of the detection zones and (ii) one or more focus settings forsubject(s) and/or object(s) detected in each detection zone in a videoor image from the camera; indicating in the graphics focus changes,adjustments or corrections to a lens of the camera that will bring thesubject(s) and/or object(s) in detection zones that are out of the depthof field of the camera into focus; and displaying the video or image ona display, and overlaying or superimposing the graphics on the displayedvideo or image. In a further embodiment, the graphics further indicate adetection zone in which one or more subjects or objects are within thedepth of field of the camera.

In further embodiments, the method further comprises (i) changing oradjusting the focus of the lens to bring into focus the subject(s)and/or object(s) in one or more detection zones that are out of thedepth of field of the camera (e.g., not in focus), and/or (ii)irradiating the subject(s) or object(s) in a field of view of the camerawith radiation, detecting radiation reflected from the subject(s) orobject(s), and calculating the distance(s) from the reflected radiationto determine the distance(s) of the subject(s) or object(s) in each ofthe detection zones.

FIG. 8 shows an exemplary method 400 of focusing a camera. In oneembodiment, the camera is a motion picture camera, and the methodfocuses the camera on one or more subjects or objects in a plurality ofdetection zones in a video. In a first step, one or more subject(s)and/or object(s) in a field of view of the camera are irradiated with aradiation beam from a distance measuring device at 410, and theradiation reflected from the subject(s) and/or object(s) is detected, asdescribed herein. For example, to minimize (i) the risk of damage orinjury to the subject(s) and/or object(s) and (ii) the potentialdisruption to filming or recording the video, the radiation may consistof infrared (IR) light. Prior to irradiating the subject(s) and/orobject(s) and detecting the reflected radiation, the distance measuringdevice may be attached above and/or adjacent to the camera's lens. Theemitter of the distance measuring device is aimed in the same directionas the optical axis of the lens. In various embodiments, the distancemeasuring device has a threaded coupling mechanism thereon for mountingto a matte box bar, standard camera accessory mount or coupling device(e.g., a Schulz Quickfix accessory mount), or Noga style arm. Power(e.g., 10-30 V DC from a battery or an AC-DC converter) may be suppliedto the distance measuring device through a power port (e.g., a 2-pinpower connector). In one embodiment, the distance measuring device cantransmit and receive electrical signals to and from a motor control,data processing and communication unit of the camera through a serialport and/or connection (e.g., a USB cable or wire) on each device/unit.

At 420, the distance(s) of the subject(s) and/or object(s) in each of aplurality of detection zones are simultaneously calculated from thedistance measuring device using the reflected radiation, in a mannerknown to those skilled in the art and corrected as explained above.Optionally, the distance(s) of the subject(s) and/or object(s) from thedistance measuring device are calculated using characteristics (e.g.,the wavelength[s], intensity, etc.) of the radiation beam.

At 430, graphics are generated that indicate (i) a field of detectionand a position for each of the detection zones and (ii) one or morefocus settings for subject(s) and/or object(s) detected in eachdetection zone in a video or image from the camera. The graphics alsoindicate at 440 the focus changes to the camera lens that will bring thesubject(s) and/or object(s) in detection zones that are out of the depthof field of the camera into focus. In many embodiments, the graphicsalso indicate all of the detection zones in which one or more subjectsor objects are within the depth of field of the camera (e.g., that arein focus) at 445. Lens setting data, in the form of overlaid textaccompanying the graphics, can indicate in addition to the lenssetting(s) the near and far limits of the depth of field.

Prior to generating the graphics, the graphics overlay unit can beattached to the back of, or connected inline with, a viewing monitor.Generally, there are at least three connections to the graphics overlayunit: power, video input and video output. Each of the video input andvideo output may comprise an HD-SDI or HDMI standard connection, and becarried over a BNC cable, among others. Parallax correction of theposition of the distance measuring device relative to the camera lenscan be determined, calculated and/or controlled using a graphics overlaymenu (e.g., commands and inputs displayed, entered and/or selected onthe monitor).

At 450, the video or image is displayed on a display (e.g., a monitor orscreen), and the graphics are overlaid or superimposed on the displayedvideo or image. The graphics may comprise a horizontal array ofdetection zones (e.g., zones 251-266 in FIG. 5, in sequence along ahorizontal axis), or a two-dimensional array of zones (e.g., arranged asx rows and y columns, where x and y are integers of at least 2, asdescribed herein). The graphics indicate (i) a field of detection and aposition for each of the detection zones, (ii) one or more focussettings for the subject(s) and/or object(s) in the video or image thatare detected in each detection zone, and (iii) the focus changes oradjustments (and optionally, the iris and/or zoom changes oradjustments) to the camera lens that will bring into focus thosesubject(s) and/or object(s) in detection zones that are out of the depthof field of the camera. The graphics may also indicate those detectionzones, if any, in which one or more subjects or objects are within thedepth of field of the camera (e.g., that are in focus).

At 460, it is determined whether to change focus to a different subjector object. If not, the method 400 simply continuously irradiates thesubject(s) and/or object(s) in the field of view with the radiationbeam, detects the radiation reflected from the subject(s) and/orobject(s), and calculates the distance(s) of the subject(s) and/orobject(s) in each of the detection zones from the distance measuringdevice. If so, the detection zone including the different subject orobject is selected, then the focus (and optionally, the iris and/orzoom) settings or position of the lens is changed or adjusted to bringthe subject(s) and/or object(s) in the selected detection zone intofocus. Because filming and/or video recording is a continuous process,the subject(s) and/or object(s) in the field of view of the camera arecontinuously irradiated, the reflected radiation continuously detected,and the distance(s) of the subject(s) and/or object(s) in each of thedetection zones from the distance measuring device continuouslycalculated (and any changes in the direction or magnitude of the changesneeded to bring onto focus subjects and/or objects that are not in focusare updated in the graphics) as described herein.

Exemplary Software

The present disclosure also includes algorithms, computer program(s),computer-readable media and/or software, implementable and/or executablein a general purpose computer or workstation equipped with aconventional digital signal processor, and configured to perform one ormore of the methods and/or one or more operations of the hardwaredisclosed herein. Thus, a further aspect of the invention relates toalgorithms and/or software that create or generate graphics thatindicate a focus state for one or more subjects and/or objects in eachof a plurality of detection zones of a distance measuring device, and/orthat implement part or all of any method disclosed herein. For example,the computer program or computer-readable medium generally contains aset of instructions which, when executed by an appropriate processingdevice (e.g., a signal processing device, such as a microcontroller,microprocessor or DSP device), is configured to perform theabove-described method(s), operation(s), and/or algorithm(s).

The computer-readable medium may comprise any medium that can be read bya signal processing device configured to read the medium and executecode stored thereon or therein, such as a floppy disk, CD-ROM, magnetictape or hard disk drive. Such code may comprise object code, source codeand/or binary code. The code is generally digital, and is generallyconfigured for processing by a conventional digital data processor(e.g., a microprocessor, microcontroller, or logic circuit such as aprogrammable gate array, programmable logic circuit/device orapplication-specific integrated circuit [ASIC]).

Thus, an aspect of the present invention relates to a non-transitorycomputer-readable medium, comprising a set of instructions encodedthereon adapted to generate graphics that assist in focusing a camera,the graphics indicating (i) a field of detection and a position for eachof a plurality of detection zones of a distance measuring device, (ii)one or more focus settings for subject(s) and/or object(s) detected ineach detection zone in a video or image, (iii) focus changes,adjustments or corrections to a lens of the camera that will bring thesubject(s) and/or object(s) in detection zones that are out of the depthof field of the camera into focus, and (iv) any detection zone in whichone or more subjects or objects are within the depth of field of thecamera; and overlay or superimpose the graphics on a displayed video orimage from the camera. The detection zones shown by the graphics thatare, in turn, generated by the software generally comprise a horizontalarray of detection zones, as described herein. However, the detectionszones may also be displayed as a two-dimensional array of detectionzones, as described herein. The field of detection and the position ofeach of the plurality of detection zones may be determined from thedistances of the subject(s) or object(s) in the field of view of thecamera. Using the known distance data and the focal length of the cameralens, the present software can simultaneously determine the focus, iris,and zoom setting changes that will bring the subject(s) and/or object(s)in detection zones that are out of focus into sharp focus, and overlaygraphics indicating the direction and magnitude of such setting changesonto the video or image. The present software can also add lens settingdata as overlaid text accompanying the graphics. Such text can alsoindicate the near and far limits of the depth of field.

CONCLUSION/SUMMARY

Thus, the present invention provides methods, apparatuses, systems andsoftware for focusing a camera. The camera focusing system generallycomprises (a) a distance measuring device, (b) a video receiverconfigured to receive video and/or images from the camera, (c) agraphics overlay unit, and (d) a monitor. The distance measuring devicecomprises an emitter configured to emit a beam of radiation, a detectorconfigured to detect one or more reflections of the beam of radiation,and logic configured to determine and process distance information forone or more subjects or objects in each of a plurality of detectionzones in a field of view of the camera from the reflections. Thegraphics overlay unit receives video and/or image information from thevideo receiver and the distance information from the distance measuringdevice, and comprises a video overlay and data processing unitconfigured to generate graphics indicating (1) a field of detection andposition for each of the plurality of detection zones and (2) adirection and/or magnitude of a change or correction in focus setting(s)for the subjects or objects within each detection zone not within adepth of field of the camera (e.g., to bring a subject or object intofocus). The monitor displays the video and/or images from the camera andthe graphics overlaid on the displayed video and/or image.

The camera system generally comprises the present camera focusingsystem, a camera with a lens and a video transmitter unit that transmitsa video or image signal output, a motor control and data processing unitconfigured to (i) adjust focus, iris, and zoom settings of the cameraand (ii) transmit lens setting data to the video overlay and dataprocessing unit, a video receiver configured to receive the video orimage signal output, and a display device configured to display thevideo or image of the video or image signal output and the graphicsoverlaid on the video or image. The method of focusing generally usesthe present camera focusing system to focus the camera, and comprisessimultaneously determining a distance from a distance measuring deviceto one or more subjects and/or objects in each of a plurality ofdetection zones of the distance measuring device; generating graphicsindicating (i) a field of detection and a position for each of thedetection zones and (ii) one or more focus settings for subject(s)and/or object(s) detected in each detection zone in a video or imagefrom the camera; indicating in the graphics focus changes, adjustmentsor corrections to a lens of the camera that will bring the subject(s)and/or object(s) in detection zones that are out of the depth of fieldof the camera into focus; and displaying the video or image on adisplay, and overlaying or superimposing the graphics on the displayedvideo or image. The software creates graphics that are useful in thepresent method and camera focusing system. The graphics indicate (i) thefield of detection and position for each of a plurality of detectionzones of the distance measuring device, (ii) one or more focus settingsfor subject(s) and/or object(s) detected in each detection zone, (iii)focus changes, adjustments or corrections to the camera lens that willbring the subject(s) and/or object(s) in detection zones that are out ofthe depth of field of the camera into focus, and (iv) any detection zonein which one or more subjects or objects are within the depth of fieldof the camera. The software also overlays or superimposes the graphicson a video or image from the camera displayed on a screen or monitor.

The present invention overcomes disadvantages of autofocus devices byproviding a mechanism for the user to manually adjust the focus onmoving subjects with high accuracy. The present invention advantageouslyprovides a method and system for the user to accurately focus theshooting lens of a motion picture camera using graphics overlaid on theimage captured by the camera. The overlaid graphics can indicate boththe direction and magnitude of distances between the plane of focus ofthe camera lens and each of a plurality of subjects and/or objectswithin a plurality of detection zones in the detection field of thedistance measuring device. Thus, the present invention enables motionpicture and photography professionals to maintain continuously sharpimages while people and things move around in real life or in movingpictures/video.

The foregoing descriptions of specific embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The embodiments were chosen and described in order to bestexplain the principles of the invention and its practical application,to thereby enable others skilled in the art to best utilize theinvention and various embodiments with various modifications as aresuited to the particular use contemplated. It is intended that the scopeof the invention be defined by the Claims appended hereto and theirequivalents.

What is claimed is:
 1. A focusing system for a video or motion picture camera, comprising: a. a distance measuring device, comprising: i. an emitter configured to emit a beam of radiation, ii. a detector configured to detect one or more reflections of the beam of radiation, and iii. logic configured to determine distance information for one or more subjects or objects in each of a plurality of detection zones in a field of view of the video or motion picture camera from the reflections; b. a graphics overlay unit configured to receive video information from the video or motion picture camera and the distance information from the distance measuring device, the graphics overlay unit comprising a video overlay and processing unit configured to generate graphics indicating (1) a field of detection and position for each of the plurality of detection zones and (2) a direction and a magnitude of a change in focus setting(s) for the subject(s) or object(s) within each detection zone not within a depth of field of the video or motion picture camera; and c. a monitor configured to display video from the video or motion picture camera and the graphics overlaid on the displayed video.
 2. The focusing system of claim 1, wherein the detection zones include a two-dimensional array of the detection zones along horizontal and vertical axes across the field of view of the video or motion picture camera.
 3. The focusing system of claim 1, wherein the graphics indicate the direction and the magnitude of the change in the focus setting(s) that will achieve sharp focus on at least one of the one or more subjects or objects in a selected detection zone.
 4. The focusing system of claim 1, wherein the graphics indicate each detection zone containing the subject(s) or object(s) within the depth of field of the video or motion picture camera.
 5. The focusing system of claim 4, wherein the graphics include a scaling that indicates the positions of the detection zones for changing a focal length and angle of view of the video or motion picture camera.
 6. The focusing system of claim 4, wherein the graphics indicate a relative position of the subject(s) or object(s) within the depth of field of the video or motion picture camera.
 7. The focusing system of claim 1, wherein the graphics overlay unit further comprises a communication unit configured to receive information from a motor control, data processing, and/or communication unit on the video or motion picture camera that adjusts the focus, iris, and/or zoom settings and transmits lens setting data for the video or motion picture camera.
 8. The focusing system of claim 1, wherein the graphics further indicate a lens focal length, a T-stop setting, a camera type, a near depth of field distance, a far depth of field distance, and/or one or more image plane-to-subject distance measurements.
 9. The focusing system of claim 1, further comprising a zoom controller, a focus knob, and an iris control slider configured to control or adjust a zoom, focus or iris setting or parameter of the video or motion picture camera.
 10. The focusing system of claim 9, wherein the zoom controller comprises a joystick that controls the rate or speed with which the camera changes the focus, iris and/or zoom setting or parameter.
 11. The focusing system of claim 1, further comprising a hand control unit including a display that displays menu items for calibrating the video or motion picture camera and/or controlling focus, iris and/or zoom motors of the video or motion picture camera, and a switch for selecting the menu items on the display and/or one or more input keys for selecting displayed items or functions on the display.
 12. The focusing system of claim 11, further comprising a ring selector for selecting a focus distance, a witness mark that indicates the focus distance selected using the ring selector, and a focus knob.
 13. The focusing system of claim 11, further comprising a set of limit selection keys configured to allow a user to select limits for the focus, iris and/or zoom motors.
 14. A focusing system for a video or motion picture camera, comprising: a. a distance measuring device, comprising: i. an emitter configured to emit a beam of radiation, ii. a detector configured to detect one or more reflections of the beam of radiation, iii. logic configured to determine and process distance information for one or more subjects or objects in each of a plurality of detection zones in a field of view of a video or motion picture camera from the reflections, and iv. circuitry configured to automatically focus on a selected subject or object in a selected one or more of the plurality of detection zones; b. a graphics overlay unit configured to receive video information from the video or motion picture camera and the distance information from the distance measuring device, the graphics overlay unit comprising a video overlay and data processing unit configured to generate graphics indicating a field of detection and a position of an auto-focus detection zone, the position of the auto-focus detection zone corresponding to the selected one or more of the plurality of detection zones; and c. a monitor configured to display the video from the video or motion picture camera and the graphics overlaid on the displayed video.
 15. The focusing system of claim 14, wherein the video overlay and data processing unit is further configured to generate graphics indicating a field of detection and position for each of the plurality of detection zones, and the graphics overlay unit is further configured to replace the graphics indicating the positions of each of the plurality of detection zones with a graphic indicating the position of the auto-focus detection zone.
 16. A video or motion picture camera system, comprising: a. the video or motion picture camera focusing system of claim 1; b. the video or motion picture camera, with a lens and a video transmitter unit that transmits a video signal; c. a motor control unit configured to (i) adjust focus, iris, and/or zoom settings of the video or motion picture camera and (ii) transmit lens setting data to the video overlay and processing unit; d. a video receiver configured to receive the video signal; and e. a display device configured to display the video of the video signal and the graphics overlaid on the video.
 17. The video or motion picture camera system of claim 16, wherein the graphics include a two-dimensional array of detection zones.
 18. The video or motion picture camera system of claim 16, further comprising a data processor configured to (i) correct the distances measured by the distance measuring device for an offset from the distance measuring device to a predetermined location in an image plane of the video or motion picture camera and/or (ii) calculate the distances along an optical axis of the video or motion picture camera from the image plane to the subject(s) and/or object(s) in each of the detection zones.
 19. A video or motion picture camera system, comprising: a. the video or motion picture camera focusing system of claim 14; b. the video or motion picture camera, with a lens and a video transmitter unit that transmits a video signal; c. a motor control unit configured to (i) adjust focus, iris, and/or zoom settings of the video or motion picture camera and (ii) transmit lens setting data to the video overlay and processing unit; and d. a display device configured to display the video of the video signal and the graphics overlaid on the video.
 20. A non-transitory computer-readable medium, comprising a set of instructions encoded thereon adapted to: a. generate graphics that assist in focusing a video or motion picture camera, the graphics indicating: i. a field of detection and a position for each of a plurality of detection zones of a distance measuring device, ii. one or more focus settings for subject(s) and/or object(s) detected in each detection zone in a video, and iii. focus changes, adjustments or corrections to a lens of the video or motion picture camera that will bring the subject(s) and/or object(s) in detection zones that are out of the depth of field of the video or motion picture camera into focus; and b. overlay or superimpose the graphics on a displayed video from the video or motion picture camera.
 21. The computer-readable medium of claim 20, wherein the plurality of detection zones comprises a two-dimensional array of detection zones.
 22. The computer-readable medium of claim 20, the set of instructions being further adapted to replace the graphics indicating the position(s) of the detection zones with a graphic indicating an auto-focus detection zone, the position of the auto-focus detection zone corresponding to one or more of the detection zones, and to automatically focus the video or motion picture camera on a selected subject or object in the auto-focus detection zone. 